set_poster_frame

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false. The description adds that this is a write operation for a thumbnail at a specific time, which is consistent but does not disclose additional traits like whether previous poster frames are overwritten or if there are any side effects. The description provides some context beyond annotations but not extensive.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single concise sentence that efficiently conveys the essential information without any redundant or superfluous content. It is well-structured and front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple setter tool with full schema coverage and no output schema, the description adequately covers the core functionality. It is complete enough for an agent to understand the purpose, though it could mention any restrictions on supported item types. The low complexity justifies a high score.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% with both parameters having clear descriptions. The description's mention of 'poster frame' and 'at a specific time' aligns with the schema but adds no new meaning beyond what the schema already provides. Baseline score of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'Set', the resource 'poster frame (thumbnail) for a project item', and the scope 'at a specific time'. It effectively distinguishes from siblings by specifying a unique action not covered by other tools like 'set_clip_start_time' or 'set_frame_blend'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. It does not mention prerequisites, when not to use, or reference any sibling tools, leaving the agent without context for decision-making.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.